1. Technical Field of the Invention
The present invention relates to a panel carrying device which carries a panel to be molded with a press.
2. Description of the Related Art
For example, since a press molded article such as a panel for an automobile has a complicated shape, a molding step is divided into several stages, and the article is molded by linearly arranged molds. In transfer press and tandem press using such a plurality of presses, a panel carrying device is disposed in order to carry a panel molded with a certain press to the next press in order.
As the panel carrying device for the transfer press, a cross bar type carrying device of [Patent Document 1] has heretofore broadly been used.
This device includes: a lift beam extended over the whole region of each press station and liftably disposed in a line direction; a carrier suspended from the lift beam so as to reciprocate between the stations in the line direction; a cross bar incorporated in the carrier; and a work holding tool attached to the cross bar, and the device simultaneously or intermittently carries workpieces of the stations.
Such a cross bar type carrying device has the following characteristics.
(1) A cam driving system or a motion control by an AC servo motor produces a feed motion of a molded panel between press stations.
(2) The panel is carried by a synthesized motion in a feed direction (horizontal direction) and a lift direction (perpendicular direction), and a vacuum cup attached to a carrying tool referred to as the cross bar adsorbs the panel to carry it.
(3) The cross bars among the press stations are connected to one another in both the feed direction and the lift direction, and the cross bars are interlocked to perform the same motion.
(4) Feed arms to produce the feed motion between the stations are arranged on a front side or a rear side of a series of feed units each usually constituted of a carriage connecting the cross bars to each other and a connecting mechanism, and the feed motion is produced by swinging of the arms.
Moreover, in addition to the above cross bar type carrying device, there are proposed panel carrying devices of Patent Document 2, Patent Document 3, and the like.
[Patent Document 1]
Japanese Patent Application Laid-Open No. 10-328766
[Patent Document 2]
Japanese Patent Application Laid-Open No. 7-73756
[Patent Document 3]
U.S. Pat. No. 6,382,400
In “Transfer Feeder” of “Patent Document 2”, a pair of lift beams vertically moved by a lifter is provided with a plurality of carriers self-operated independently with a linear motor, and the work (panel) can be carried at a high speed by use of the linear motor as a driving source.
In “Transfer Press Carrying Device” of [Patent Document 1], the lift beam is provided with a plurality of carriers, and the carriers can carry the works (panels) at the high speed by use of a servo motor as the driving source.
In “Transport and Positioning System” of “Patent Document 3” as shown in FIG. 1 includes a driving device 30 provided with a lever mechanism 23 having an output section 25 to drive and position a cross bar 22. This lever mechanism 23 has a swing arm 24 forming the output section 25 on one end, and this output section 25 is connected to the cross bar 22. The swing arm 24 is connected to two points of a support point 28 and a driving point 33 at an interval. The interval between the support point 28 and the driving point 33 is shorter than an interval between the output section and the support point. It is to be noted that in this figure, 21 is each work holding tool attached to the cross bar 22, 32 is a guide rod which connects a slide block 37 to the driving point 33, 41 is a swing motor which swings and drives the guide rod 32, and 45 is a translatory device which vertically moves the slide block 37.
According to this constitution, the translatory device 45 vertically moves the slide block 37, and the swing motor 41 swings the guide rod 32 to thereby drive and position a distant end (driving point 33) of the guide rod 32, and a movement of the rod is enlarged at a lever ratio to drive and position the cross bar 22 to which the work holding tools are attached.
However, the above devices of [Patent Document 1] have the following problems.
(1) Different motions cannot be imparted to the cross bars.
(2) Since the cross bars for all the stations are simultaneously moved, the servo motor and a feed driving unit enlarge.
(3) Since motion curves for the press stations are the same, there occurs a necessity of devising a mold shape in order to avoid interference, and it is difficult to cope with molding of various plates.
Moreover, in a linear motor system of [Patent Document 2], the work can be fed at the high speed by the linear motor, but a separate lift mechanism is required, and the whole structure becomes complicated and enlarged.
In an AC servo system of [Patent Document 1], a high rigidity cannot be obtained owing to a serial link.
In a swing arm system of [Patent Document 3], the swing arm carries the panel. The longer a carrying distance is, the more the arm needs to be lengthened. Deflection or the like of the arm causes vibration.
Furthermore, in a case where the work holding tools are swung (tilted) in order to cope with complicated press molding, a tilting device needs to be separately disposed on the cross bar, and the structure becomes complicated. There are problems that a weight of a movable portion increases, and it becomes further difficult to achieve the high speed.